The parity check was the auto started un-correcting one. How do you know that it wrote the data back successfully? I'd like to be able to verify that in the future on my own. The process had 0 sync errors so I think I'm confusing myself on parity errors vs read errors, or just don't understand the way Unraid is reporting to me.
I agree about the drive looking like it's in bad shape, but wanted to get a second set of eyes on it to make sure I didn't replace anything unnecessarily. It's one of my newer 3 TB drives but won't be any issue to replace. As long as I can do it safely.
As far as replacing the drive, I just need to remove it from the array and let it rebuild to a replacement drive. Will the existing read errors affect that process? I have a known good 3tb that I removed in the past to upgrade to a larger drive that will replace it just fine.